public static IWebHostBuilder CreateWebHostBuilder()

in src/WebJobs.Script.WebHost/Program.cs [39:100]
55 lines of code
4 McCabe index (conditional complexity)

        public static IWebHostBuilder CreateWebHostBuilder(string[] args = null)
        {
            // Setting this env variable to test placeholder scenarios locally.
#if PLACEHOLDER_SIMULATION
            SystemEnvironment.Instance.SetEnvironmentVariable(EnvironmentSettingNames.AzureWebsitePlaceholderMode, "1");
            SystemEnvironment.Instance.SetEnvironmentVariable(EnvironmentSettingNames.AzureWebsiteContainerReady, "0");
#endif

            return AspNetCore.WebHost.CreateDefaultBuilder(args)
                .ConfigureKestrel(o =>
                {
                    o.Limits.MaxRequestBodySize = ScriptConstants.DefaultMaxRequestBodySize;
                })
                .UseSetting(WebHostDefaults.EnvironmentKey, Environment.GetEnvironmentVariable(EnvironmentSettingNames.EnvironmentNameKey))
                .ConfigureServices(services =>
                {
                    services.Configure<IISServerOptions>(o =>
                    {
                        o.MaxRequestBodySize = ScriptConstants.DefaultMaxRequestBodySize;
                    });
                })
                .ConfigureAppConfiguration((builderContext, config) =>
                {
                    // replace the default environment source with our own
                    IConfigurationSource envVarsSource = config.Sources.OfType<EnvironmentVariablesConfigurationSource>().FirstOrDefault();
                    if (envVarsSource != null)
                    {
                        config.Sources.Remove(envVarsSource);
                    }

                    config.Add(new ScriptEnvironmentVariablesConfigurationSource());

                    config.Add(new WebScriptHostConfigurationSource
                    {
                        IsAppServiceEnvironment = SystemEnvironment.Instance.IsAppService(),
                        IsLinuxContainerEnvironment = SystemEnvironment.Instance.IsAnyLinuxConsumption(),
                        IsLinuxAppServiceEnvironment = SystemEnvironment.Instance.IsLinuxAppService()
                    });
                    config.Add(new FunctionsHostingConfigSource(SystemEnvironment.Instance));

                    var hostingEnvironmentConfigFilePath = SystemEnvironment.Instance.GetFunctionsHostingEnvironmentConfigFilePath();
                    if (!string.IsNullOrEmpty(hostingEnvironmentConfigFilePath))
                    {
                        config.AddJsonFile(hostingEnvironmentConfigFilePath, optional: true, reloadOnChange: false);
                    }
                })
                .ConfigureLogging((context, loggingBuilder) =>
                {
                    loggingBuilder.ClearProviders();

                    loggingBuilder.AddDefaultWebJobsFilters();
                    loggingBuilder.AddWebJobsSystem<WebHostSystemLoggerProvider>();
                    loggingBuilder.Services.AddSingleton<DeferredLoggerProvider>();
                    loggingBuilder.Services.AddSingleton<ILoggerProvider>(s => s.GetRequiredService<DeferredLoggerProvider>());
                    loggingBuilder.Services.AddSingleton<ISystemLoggerFactory, SystemLoggerFactory>();
                    if (context.HostingEnvironment.IsDevelopment())
                    {
                        loggingBuilder.AddConsole();
                    }
                })
                .UseStartup<Startup>();
        }